Hair coloring has long been a very large industry for a very long time. Today, it is an enormous industry in the U.S. alone.
For example, a First Research report states that, in 2014, there were 82,000 hair salons in the U.S. alone, in addition to 4,000 barber shops. A 2008 Clairol Survey reported that 75% of women in the U.S. between 18 and 65 years of age color their hair, and that 88% of women feel that their hair has an effect on their confidence. Multi-Sponsor Surveys reported in 2012 that 11% of men aged 50-64 color their hair.
A 2005 P&G Beauty Study done by Dr. Frauke Neuser showed that, of the women who color their hair, 52% do so at home only and 48% do so at a Salon (28% at a salon only and 20% at a salon and at home). In 2015, Modern Salon Media conducted a Process Haircolor Research Study, which found that the number one1 reason all women surveyed—home color consumers and salon clients combined—say they color their hair is to color gray and look younger (46%). For women 35 and older, gray coverage becomes even more important, at 65%. This same study found that 48% of salon color clients say they visit a salon every six weeks or more often for services, and 52% visit less frequently and that the overall average interval between salon visits is 7.5 weeks. This same survey found that most salon professionals (64%) say they recommend a “root cover-up” between color appointments, provided either professionally or by use of off-the-shelf coloring products, but 74% of color clients say they have either never had a root cover-up or are unsure if they have ever had one.
Since human hair generally grows at the rate of ½ inch per month, the enormous number of people who have hair coloring done professionally are experiencing substantial regrowth of uncolored hair between coloring services. For most people, the mismatch regrowth is quite visible in the front hairline and hair part within 2 to 3 weeks after a hair color treatment.
How Hair Coloring Works:
The visible part of the hair that is protruding from the skin is called the shaft. The structure of hair shaft is made up the three layers. The outer layer is called the cuticle and consists of overlapping dead cells (like roof shingles) which protect the inner layers. When the cells lie flat the hair reflects light, and looks shiny. When the cells of the cuticle layer are open, the hair feels rough, dry, and looks dull.
The next layer is called the cortex. This is the layer that contains pigment, called melanin, that gives hair it's color.
The innermost layer is called the medulla. This layer is not involved in the color process.
There are three main compounds present in hair dye: ammonia; hydrogen peroxide, and dye intermediates and couplers. Hair typically has a pH level of 5. Ammonia, which is alkaline, is used to initiate the color process by swelling the hair shaft and opening up the cuticle layer.
Hydrogen peroxide is an acid that causes oxidation. The oxidation decolorizes (lightens) natural melanin pigment in the hair cortex and reacts with the color molecules of the chosen permanent hair color pigment to form dye molecules that cannot be washed out.
Hydrogen peroxide is added to hair dye in different concentrations. These concentrations are measured by how many volumes of oxygen are liberated from the decomposition of the hydrogen peroxide, meaning that 10 volume peroxide will form 10 volumes of oxygen from a single volume developer. The higher the concentration of developer, the more oxidation that will occur in a client's hair.
Hydrogen peroxide thus initiates the color process and creates longer lasting color. The larger the volume of peroxide, however, the greater the amount of sulfur is removed from the hair. Loss of sulfur causes hair to harden and lose weight. This is why for most hair coloring services, the peroxide level is maintained at 30 volume or less.
The dye or coloring intermediates and couplers are small compounds that fit into the opened cuticle of the hair shaft. Once they mix with hydrogen peroxide, they become larger color molecules that cannot depart the hair shaft.
How Professional Permanent Hair Color is Used:
The professional hair colorist begins by examining the clients hair texture, dryness, natural hair color, and amount of gray hair, which is coloring resistant. From those factors the colorist determines the formulation of various pigments (dye) and enhancers to be used to achieve the desired result. Next, the colorist determines the volume of peroxide required according to the various factors. Then the colorist blends the pigment formulation with the peroxide formula. When the mixture is completely blended, it is applied to the client's hair.
The chemical process of pigment (color) becoming permanent in the hair shaft usually requires between 20-30 minutes to complete. The color formulation remains on the clients hair for that period of time in order to fully develop (replace color in the client's hair). After the prescribed period of time for development, the color molecules of the permanent hair color have expanded and are permanently fixed into the hair shaft. The hair is then shampooed, rinsed, and styled.
Because the peroxide component (H2O2, more fully referred to as “hydrogen peroxide”) is an acid, it is typically pre-mixed with water to dilute the peroxide in the resulting peroxide/water mixture. Nevertheless, even with this lower concentration of peroxide, if the resulting hair color formulation of colorant, water, and peroxide makes contact with human skin or hair for too long or with an excessive concentration of peroxide, the peroxide in the formulation can excessively oxidize, excessively dry, and damage the skin or hair or at least leave it with a dull finish or lack of shine. This is one reason why the professional colorist usually applies the colorant formulation with plastic gloves, to protect the colorist's skin from contact with the peroxide component of the formulation. This is also why the professional colorist makes adjustments to the colorant formulation applied to a given client in repeat coloration sessions over time, to ensure that the client's hair remains in a healthy condition. These risks are reasons that hair coloring is so commonly performed by a professional hair colorist.
Another reason is that, as noted above, the colorant component is typically customized by the professional colorist, by mixing one or more color components (usually at least two to three pigments or dyes), often with one or more other enhancers, to yield the color shade desired in the resulting colorant formulation. The professional hair colorist typically has in-depth knowledge of differing brands of hair coloring components and their differing qualities; and this knowledge plays a crucial role in adjusting the shades and strength of colors for differing clients, including by taking into account each client's hair texture, dryness, hair density, and natural color, including the amount of gray hair. After sufficient processing time in the client's hair, which can vary by client, the colorist rinses the client's hair to remove remaining colorant formulation not absorbed the hair. For all these reasons and others, such as convenience and combining the hair coloring process with procuring a haircut, clients seeking hair coloring commonly have the hair coloring formulation prepared and applied by professional hair colorists rather than by the clients on their own.
The Age-Old Problem of Hair Regrowth after Hair Coloring:
Within one to two weeks after hair is colored by professional colorists, clients typically experience visible naturally-colored hair regrowth, particularly around their front hairlines and at any parting lines within their hair. Since most hair color clients do not have the time or money to have their hair color professionally retouched every one to two weeks, their only options are to either maintain the visible regrowth, or to try and match the professional color with a hair coloring product acquired at a store or from an online commercial source.
The latter nonprofessional hair color products are, however, vastly inferior to professional hair coloring. One reasons is because over-the-counter products, designed as one size fits all, typically include an excessive concentration of peroxide—sometimes close to 40 volume in order to ensure maximum coloring of resistant gray hair—as compared to the much lower concentration that would be utilized by professional colorists for most clients.
In addition, since, as noted above, the professional colorist typically mixes different colors and possibly enhancer—often multiple different enhancers as well—to achieve a desired hair color shade for the client's particular type of hair and natural color, the client usually does not have the knowledge or formulation components to achieve anything close to the professional's hair color shade in the client's hair. The results of a non-professional use of off-the-shelf hair coloring products commonly are bands of colors that do not match, do not last and or easily washed out by shampooing, can cause the scalp to itch, and/or do not provide the desired resulting hair color, particularly in grey hair.
With regard to grey hair in particular, many off the shelf retouching products contain little or no peroxide. With little or no peroxide in the hair coloring formulation, grey hair cuticle in particular does not open and therefore does not become colored.
For these and other reasons, it is also common for clients who use home coloring products or kits to at least eventually experience an undesirable result in hair color and hair damage. When this occurs to given client, the client's choices are to either live with the problem until the client's hair grows out, or have the problem corrected by a professional colorist. The corrective process is typically much longer and more expensive that normal professional coloring services, and the process usually yields yet further dryness and hair breakage.
So, while home-hair color products have long been widely available and themselves a substantial part of the huge hair coloring industry, they have long provided results that are inferior to the typically much more aesthetically attractive results of professional hair coloring, including when used to re-touch hair color between professional coloring sessions. At the same time, professional colorists have typically constantly sought additional ways to enhance their product and service offerings and increase resulting profitability as well. This has been the state of the hair coloring industry for well over 40 years.